The use of polymeric materials as semi-permeable membranes is well known. Such polymeric materials may include, for example, aromatic polyimides, polyesters and polyamides as shown in U.S. Pat. No. 3,899,309.
Various methods are known for manufacture of polyethers such as polycyanoarylethers. U.S. Pat. No. 3,730,946 shows manufacture of cyanoaryloxy polymers by reacting a dinitrobenzene that has a cyano group attached directly to the benzene nucleus, with an alkali metal salt of a divalent, carbocyclic, aromatic radical in the presence of a dipolar aprotic solvent. U.S. Pat. No. 3,730,946, however, does not suggest that cyanoaryloxy polymers have utility as semi-permeable gas separation membranes.
U.S. Pat. No. 4,640,975 relates to polycyanoarylethers which show excellent heat resistance and fire retardance. These polycyanoarylethers are formed by reacting a dihalobenzonitrile with an alkali metal salt of dihydroxynaphthalene in the presence of a solvent. U.S. Pat. No. 4,640,975, however, does not suggest utility of polycyanoarylethers as semi-permeable separation membranes.
U.S. Pat. No. 4,812,507 relates to polycyanoarylethers and methods for their preparation. This patent, like U.S. Pat. No. 4,640,975, also does not suggest utility of polycyanoarylethers as semi-permeable separation membranes.
Aromatic polyether nitriles have been synthesized in the art. Examples of synthesis procedures are shown in D. K. Mohanty et al, "Synthesis and Characterization of Polyarylene Ether Nitriles", Polymer Preprints, 27 (1) pp. 147-149, (1986), and in D. K. Mohanty et al, "Poly(Arylene Ether Sulfones) and Related Materials Via A Potassium Carbonate, N-Methyl Pyrrolidone Process", Polymer Preprints, 23 (1), pp. 284-286, (1982).
As indicated, the semi-permeable membranes of the prior art have been provided as polymers such as imides, esters, amides, and the like. Although these polymers have been found suitable for separating a wide variety of gaseous mixtures, these materials can be costly to manufacture due to the need for expensive reactant materials. Moreover, some of these polymers are susceptible to moisture degradation which leads to reduced performance. A need, therefore, exists for semi-permeable membrane materials which may be inexpensively manufactured and which show superior gas separation properties while overcoming the performance limitations of the membranes of the prior art.